Moving effortlessly at 289 pounds, Armstead blasted through position drills and tests, posting a 9' 10" broad jump, 30" vertical jump and strong times in the three-cone drill and short shuttle. The only disappointment came in the 40-yard dash, running a 5.05 with the wind and 5.13 into it.
With scouts from the Seahawks, 49ers, Bills, Raiders, Patriots, Rams, Falcons, Vikings, Browns, Chargers and Bengals in attendance, Armstead looked like a natural, either at defensive end in a 3-4 defense or strongside defensive end or three-technique defensive tackle in a 4-3 alignment.
What will determine his future is how team doctors evaluate Armstead's medical history.
In March 2011, Armstead was hospitalized for five days because of chest pains. He was subsequently held out of spring practice and never practiced or played again for the Trojans.
Armstead repeatedly declared himself fully healthy in the 13 months since and is confident NFL teams will feel the same way.
"I'm healthy now, so I don't see what the issue is. Been healthy for a year now," he said.
Neither Armstead and his family nor USC would disclose the exact nature of the condition, aside from a brief statement from Trojans head coach Lane Kiffin that it was not related to Armstead's heart.
Aware of the possibility of a pre-draft leak, Armstead would be okay with having the circumstances revealed but prefers to maintain his privacy.
"I don't want to clarify," he said. "It's my private medical information. I wouldn't go ask you what is your personal medical information and all your medical history.
"If it comes out, I feel like a lot of people would be comfortable with what the information is, but you have to know the whole back story and it is too much to go into. If it came out, it would be fine. If it came out, then everyone would know the truth so it doesn't really matter to me."
Those in Armstead's camp believe he would be regarded as a potential second-round pick if he had played his senior season at USC given his athleticism and versatility in a relatively weak defensive line crop, but acknowledge upcoming visits and physicals will ultimately determine his draft stock.
For his part, Armstead says he does not care where he is drafted, instead seeking a chance to showcase his skills.
"I could honestly care less," he said. "I just want an opportunity to play. I know there are a lot of teams that have high interest in me, so I'm just hoping one of those teams will pick me up. Even if it is free agency, I don't care. I want a shot to play in the NFL."
Dan Greenspan is the publisher of Cal Sports Digest and covers the Pac-12 for Fox Sports/Scout.com. Follow him on Twitter @DanGreenspan.